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Troubleshooting Basic Bends

It goes without question that many smaller elements make up a sign. And that the quality of each component contributes to the sign’s total caliber.

By Randall Caba
Reprinted with permission from Sign Builder Illustrated

This is likely truer of neon signs than most other sign types. Since each bend is individually handcrafted, the sign’s appeal, readability, strength and longevity lies within the glass blower’s skill to correctly form each and every bend and to follow a given pattern.

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  • Now, not every glassblower is a journeyman and even journeymen have bad days. So, other than raw skill what tools can aid a neon craftsman in making a quality sign?

    The Basics

    Well, most tools are simple and tangible: a metal rod or electrode shell, a metal file or blade screwdriver, a prefabricated template or jig. To know when and how to use these tools, you must first identify the unfit bend.

    To identify an unacceptable basic bend, one must scrutinize ongoing glasswork. It only takes a few seconds for the work to cool from molten to firm so little time is available for judging and repairing the ill-formed bend.

    The L-bend

    To judge the L-bend, or ninety-degree turn, look at the crease, the inside fold. Does the bend appear smooth and rounded? Is glass bunched in the crease forming what looks like a rippling muscle? Did a wedge shape appear across the bend? Or is the crease sharp without blemish?

    If the bend is smooth and rounded, likely it is somewhat elongated; during bending the glass was stretched. You can sharpen the bend by pressing inward such that, if you use three marks on the tube, the outside marks move closer. To further sharpen the bend, press the crease with a metal file edge or the edge of a blade screwdriver. This forces a square inside corner into the bend.

    A wedge shape appears across the entire bend when the glass is twisted. Use three aligned marks, a center mark and two outside heating marks, to quickly identify the error. If the marks are misarranged, simply twist one tube to realign the marks. A final quick puff of air into the tube helps round the tube and correct the appearance.

    Of course, all this troubleshooting activity must occur well within the few seconds after leaving the flame, before the molten glass firms. Otherwise, the glass is too rigid to manipulate and any extraneous activity will strain the glass eventually causing it to break.

    The U-bend

    To appraise the U-bend, Double back, or one hundred eighty-degree turns, asks these questions: Does the bend flow smoothly in an arch from one straight tube to the other? Or does it look flat, more like two L-bends? Is extra glass bunched in the center like a muscle? Or did a wedge shape appear across the bend?

    If the glass flows smoothly in an arch, the bend is probably formed correctly. However, if it looks flat, like two L-bends, either the glass has been stretched or an insufficient length of tubing was heated. See bends #3 and #4 from left to right in the photo.

    Bend #3 exhibits straight tubing between the outside marks and the curve of the bend. This denotes insufficient glass was heated. In bend #4, sufficient glass was heated however the bend was stretched. Note: all bends are over-blown to exaggerate the error.

    Again, using three marks will aid in troubleshooting. If the bend stops shy of the two outside marks, straight tubing exits between them and insufficient glass was heated. Make certain the entire length of tubing between the marks gets heated to molten before bending.

    One quick fix is to “milk” a square looking U-bend, work the outside marks closer with an alternating “up and down” motion. This effectively rounds out the bend and a final puff of air aids its appearance.

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    Now, some craftsmen grab a metal rod roughly the diameter of the inside of the desired bend. They quickly push and roll the rod against the squared U-bend, rounding it. Of course, this too must be performed quickly or a destructive strain may develop within the glass structure.

    Alternatively, some cut a metal electrode shell from its glass housing and trim its wires. They push the shell over a pencil end so that it’s always at their ready. They use it to round a muscled or square bend. See bend #2 showing the pencil and electrode shell in the photo.

    Use the “milking” method and metal rod or electrode shell to smooth a muscled U-bend too. Excess glass gathers on the bend interior when the bend is pushed together during formation. So, quickly milk the outside pencil marks away, smooth with a tool then offer that all-important final puff of air to smooth its look. See bend #1 in the photo.

    Again, a wedge shape means the glass is twisted and the three aligned pencil marks will identify the error. Simply realign the marks while molten and puff into the tube to correct the error.

    The Offset

    The Offset is just a Double back with an angle, a change of direction between the tubes. All the same methods of identifying and correcting the errors mentioned with the U-bend will work equally well with the Offset.

    Drops and Raises

    The Drop and/or Raise changes tube elevation one block high and tube direction about ninety-degrees. A properly formed bend appears like two L-bends heading off in different directions.

    The most common visible errors are twisting and glass gathering or bunching. There’s a natural twist or roll when forming this bend but excess rolling shows up clearly as ridges in the glass. And bunching is caused when too much tubing is heated and the bend formed to tall. The bend collapses upon itself when laid upon a block and the glass bunches.

    Some craftsman smooth most every bend with a block ­ yes, some still even use the outlawed asbestos for a block. They quickly run the block’s smooth edge over the bend smoothing out its surface. This is the most effective way to smooth an improperly formed Drop or Rise too. But try to stay away from asbestos.

    Templates or Jigs

    I often mention use of templates. That’s because they are cheap insurance against making a bad curved bend. They’re simple, easy to use and one is likely lying just out of reach at any given moment.

    Consider bending the perfect circle, tough to do freehand without patience and lots of skill. But somewhere in the shop lies a round object that fits the inside of the circle pattern to perfection. Look at metal cans: a coffee can, an empty and clean paint can or other.

    It’s easy to wrap most or all of a circle or letter “O” around such a container. I’ve even used a glass candy dish wrapped in non-asbestos fabric to mass-produce a certain size “OPEN” sign! Just be certain to remove the template immediately after forming the bend to reduce chance of strain within the tube.

    If a can is too small, consider cutting the shape from one-half inch or thicker plywood or pressboard. Then attach a strip or two of non-asbestos fabric along the curve to reduce burning and smoke when wrapping molten glass around it.

    Some tube benders keep several size wood templates handy for bending the occasional big or small “O”. Others bend long slow curves to wood pegs positioned on a board or to small nails, brads, tapped at an angle around the pattern. They do whatever it takes to quickly and efficiently fabricate the tube.

    Yes, a sign is the sum of its parts. And troubleshooting each and every bend helps insure the quality of the whole neon sign. Add these tips and tools to your bag of tricks and help promote the caliber of your work to the next level.

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